


Gift of the Kappa

by Moon_Blitz



Category: Dr. STONE (Manga)
Genre: Blow Jobs, M/M, Science Boyfriends, Science Experiments
Language: English
Status: Completed
Published: 2019-06-15
Updated: 2019-06-15
Packaged: 2020-05-12 12:55:16
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,982
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19229557
Author URL: https://archiveofourown.org/users/Moon_Blitz/pseuds/Moon_Blitz
Summary: Lube isn't always necessary for sex, as Senkuu reminds Taiju. Of course, he knows how to make that too.





	Gift of the Kappa

**Author's Note:**

  * For [Welsper](https://archiveofourown.org/users/Welsper/gifts).



> A big thank you to R for beta-reaidng this!

Senkuu cracked an eye open as Taiju shuddered and moaned softly beside him, listening to him pant before his breathing evened out. “I could have done that, you big oaf,” he muttered, rolling onto his back and turning his head to look at Taiju. It was too dark to see, but he sensed his friend was blushing.

“I-It’s fine, Senkuu!” Taiju stammered a moment later, confirming his theory. Taiju only stammered when flustered or excited, and in this case, he was both. “You need your rest, anyway.”

Snorting, Senkuu replied, “It’s winter now. Aside from working on the depetrification formula, there’s not much for me to do. Besides, what you really want is to have sex, right?” Taiju made a gurgling sound, clearly too embarrassed to forum a coherent sentence, so he continued.

“I was ten billion percent sure that you’d bring it up before now, since I know you’ve been jerking off in private.” Senkuu reached out, tracing a finger down Taiju’s shoulder and over his bicep, feeling his boyfriend shiver in response. “I also know you spent three thousand years trapped in stone, but surely you didn’t forget that there’s more than just anal sex, right? If you wanted me, all you had to do was ask.”

“You’ve been so busy with the formula, I didn’t want to distract you,” Taiju said weakly, his hand suddenly covering Senkuu’s. His _sticky_ hand.

Senkuu winced and pulled away, mind made up. Pushing back the futon covers, he got up and stirred the fire in the brazier back to life, adding some more charcoal to make sure the room stayed warm for the rest of the night. Not that he needed it in bed – Taiju was a furnace in human form, but it was nice to get up to a room that wasn’t freezing.

“I could use the distraction, you know,” he said, taking a moment to bask in the heat of the fire. It was frustrating, working in such primitive conditions and making such slow progress. And he would never say it, but being without Taiju in the six months after he had awoken had been hard. Not just in terms of physical labour, but emotionally as well. Taiju had been by his side ever since they first met, and him suddenly being gone had been a blow.

“So you want to...?” Taiju’s tone was eager, and Senkuu laughed softly as he turned in time to catch the moment Taiju’s expression shifted from relaxed to excited.

“Of course,” Senkuu replied, returning to the futon and reaching out to push the already untied sleeping robe fully off of his boyfriend. He traced a finger down his boyfriend’s chest, admiring the way the glow of the fire highlighted his muscles, before turning his attention to Taiju’s growing erection.

“Hands, mouth, or both?” he asked, moving to kneel between Taiju’s spread legs.

“Both!” Taiju responded immediately, grinning as Senkuu smirked.

“Eager, are we?” he teased, taking Taiju’s cock in his hands and giving it a gentle squeeze. A groan was his only answer, so he squeezed harder before sliding his hands down to the base of the cock. Feeling Taiju twitch, he murmured, “Don’t get too excited, I’m just getting started.”

Shifting so that his mouth hovered above the tip of Taiju’s cock, he added thoughtfully, “Although it has been several thousand years since I last did this, so I suppose I can forgive you for being overstimulated.”

“Senkuu!” Taiju cried in response, an equal mix of frustration and eagerness in his tone. Senkuu glanced up to see him watching intently, eyes alight with lust.

“Fine,” Senkuu grumbled, wishing he could tease Taiju more. Next time, he resolved, dropping his head to take the head of the cock in his mouth.

“Oh, yeah!” Taiju cried, the last word turning into a moan of pleasure as Senkuu’s mouth enveloped his cock further. Senkuu closed his eyes and breathed through his nose, swiftly settling into the familiar rhythm of the blowjob. Soon enough, Taiju began to move in time with him and Senkuu pulled back a little, letting Taiju thrust into his mouth without going too deep.

As his movements became more jerky and his cries of pleasure louder, Senkuu moved so he was sucking just the head of Taiju’s cock with his hands wrapped around the rest, urging Taiju with both tongue and fingers to orgasm. He did a moment later, Senkuu swallowing the warm liquid that flowed into his mouth as Taiju shuddered and panted above him.

He took a moment to compose himself before sitting up, a wicked smile on his face. “Was that enough of a reminder to that musclebound brain of yours that anal sex isn’t the be all end all?” he teased, watching Taiju blink away his post-orgasm haze and smile back.

“Yeah, I think I got it. Still, I wish we had some lube.”

“Oh, but we do,” Senkuu said proudly, grinning as Taiju’s eyes widened. “Technically, human saliva can be used for lubricant, but if it’s all the same, I’d rather we didn’t.” It was unsanitary, and he didn’t mind putting in a little extra effort if it meant having a reliable product. Taiju winced and shook his head, clearly following his line of thought.

Sliding back beneath the futon, Senkuu stretched out on his side as he continued. “Once I knew you were going to wake up, I started experimenting. Historically, olive oil was a popular thing to use as lube, but we don’t have access to that.” Shodoshima was too far away to even contemplate visiting, and he didn’t know if the olive trees that grew there had survived the thousands of years humanity had been gone.

“You know _tororo jiru_?” At Taiju’s nod, he continued. “Before it became the name of a soup, it used to apply to the slick substance that was made when Chinese yams were grated.” Seeing Taiju’s uncomprehending look, he smiled wickedly and added, “And it just so happened that the substance made for great lube.”

“Oooooh! I remember we gathered some of those! They were really tasty, too!” Taiju exclaimed.

“They were,” Senkuu acknowledged with a nod. “But they took a lot of work to grate, so I decided not to bother.” He had had better things to spend his time on, like preparing the tree house and laboratory for Taiju’s arrival. “I thought about using clove oil, until I remembered that there was a much more common plant that was easier to work with.”

“What is it, Senkuu?” Taiju asked, practically vibrating with excitement. Now there was a thought, making a vibrator with stone-age technology. Pushing the idea aside to mull over later, Senkuu smiled at his boyfriend.

“It’s an absurdly common thing, really. Seaweed.”

 _“...Seaweed?!”_ Taiju gaped. “Like...Like nori and stuff?”

“Not quite. The seaweed we’ll be using is in the same classification division as nori, but from the _Florideophyceae_ class instead of the _Bangiophyceae_ class.” He knew the scientific terms were meaningless to Taiju, but they were important to him. Important to the humanity that he was going to rebuild.

Taiju opened his mouth to say something, but was cut off by a massive yawn. Chuckling, Senkuu scooted over to press his forehead against his boyfriend’s chest as Taiju settled beneath the futon. “How about we leave the finer details until the morning? I wouldn’t want your brain to overheat from too much information, after all.”

He both felt and heard Taiju’s laugh as he wrapped an arm around Senkuu’s waist. “Sure, Senkuu.” Closing his eyes, Senkuu breathed in deeply, relishing Taiju’s scent as he drifted off.

\- - -

“About last night...” Senkuu blinked at Taiju trailed off, wondering what could cause him to hesitate. Taiju flushed and looked away, saying quickly, “We got so caught up talking about lube, I didn’t get a chance to do anything for you. I’m sorry!”

“It’s fine, you big oaf,” Senkuu said with a wave of his chopsticks. “I was too tired to really enjoy anything anyway.” Seeing that Taiju still looked like a kicked puppy, he smiled and added, “Tonight, perhaps?”

He was relieved when Taiju nodded and smiled. “Okay! Oh, if we’re not using nori seaweed, what kind are we using?”

Of course he would switch topics like that. Senkuu swallowed his bite of grilled fish before answering. “It’s scientific name is _Kappaphycus alvarezii_ , but it’s also known as elkhorn sea moss.”

He waited for Taiju to sound the name out, being rewarded with a cry of “Kappa? Like the youkai?”

“Apparently so.” So he may have picked this seaweed because of the name over other factors, but it was laughably easy to find once he started looking, so he figured he might as well use it. “The seaweed is important because it has high amounts of something called carrageenans, which just so happened to be an important ingredient in certain brands of lube.”

“Wait, you can make lube from seaweed? That’s awesome! Science really is incredible, Senkuu!” Senkuu puffed up at the praise, letting Taiju ramble on for a minute or two before waving his chopsticks to get his attention.

“Luckily for us, Kappa-carrageenan is ten billion percent possible to make with the tools we have already. All it takes is a few containers, a fire, dry seaweed and water.” He grinned at Taiju, seeing his excitement matched in his boyfriend’s face. “Get excited, you big oaf. Let’s go make some lube.”

The moment was slightly ruined when Taiju bounded over the brazier between them and tackled him to the floor, whooping wildly in his ear. The deep kiss that followed made up for it though, and Senkuu returned it eagerly. Yes, he had definitely missed this.

\- - -

As Senkuu leaned over the bubbling pot of water, he was grateful once again for Taiju’s sheer strength. When he had done his initial experiments with the seaweed during the summer, he had only been able to carry a small amount of water from the river to his base, thereby limiting how much time he could spend working before running out of energy. But Taiju had seemingly unlimited energy, so it was a simple thing for him to haul the water Senkuu needed.

Taiju returned with the last bucket of water, setting it down away from the fire as Senkuu had directed. They needed cold water once the mixture of seaweed and water he was tending to was done boiling, and the temperature outside was low enough to keep it cold.

“Smells salty,” Taiju commented, taking the stir stick from him and stirring the mixture.

“Duh,” Senkuu said fondly. “We are dealing with seaweed after all.”

“What happens after we boil it and pour the cold water in?”

Senkuu glanced up at the sun to note the time, hiding his smile. Taiju didn’t really understand the complicated process, but he was happy that his boyfriend was asking questions all the same.

“We let it cool for a bit, then strain it and let it sit for a day. Keep stirring, but not too hard,” he added. “As it sits, it’ll form into a gel, which we can then use. Carrageenan can be added to a bunch of foods, too. Although...” Senkuu studied the seaweed mixture, reviewing what he knew of the substance. “Perhaps if we were to add a sweetener or fruit while it sets, we can make a dessert of some kind.”

“Can we try that next time?” Taiju asked eagerly, eyes sparkling with excitement.

“Sure.” Senkuu knew he had the formula for making carrageenan down pat, and this batch should last them through the winter months until seaweed started to grow again, and he had gathered enough extra that there was no harm in experimenting a bit. Taiju hummed happily as he stirred, and Senkuu decided that something sweet was the perfect reward for all of his boyfriend’s hard work.


End file.
